<!doctype html> 
<html ng-app='text'> 
<head> 
    <meta charset="utf-8"> 
    <title></title>
    <style type="text/css">


    </style> 
    <script type="text/javascript" src='angular.js'></script>
    <script type="text/javascript">
   		var app = angular.module('text',[]);
   		app.controller('const',function ($scope){
   			
   			//$scope.arr = [1,2,3];
   			$scope.a = 0;
   			$scope.$watch('a',function (){
   				alert(1);
   			},true)

   		})

    </script>
</head>
<body ng-controller='const'>
<input type='button' ng-click='arr.push(99)'>
<!--
<div ng-repeat='i in arr'>{{i}}</div>
-->
</body>
</html>